Interaction of integrins alpha 3 beta 1 and alpha 2 beta 1: potential role in keratinocyte intercellular adhesion.

Abstract

Abstract. The colocalization of integrins ot2/~ and ot3fl~ at intercellular contact sites of keratinocytes in culture and in epidermis suggests that these integrins may mediate intercellular adhesion (ICA). P1B5, an anti-u3fl~ rnAb previously reported to inhibit keratinocyte adhesion to epiligrin, was also found to induce ICA. Evidence that P1B5-induced ICA was mediated by a2/3~ and O/3/~1 was obtained using both ICA assays and assays with purified, mAb-immobilized integrins. Selective binding of ot2/3~-coated beads to epidermal cells or plate-bound O/3~31 was observed. This binding was inhibited by mAbs to integrin o~3, oL2, or fl, subunits and could be stimulated by PIB5. We also demonstrate a selective and inhibitable interaction between afffinity-purified integrins ot2/3~ and o~3/31. Finally, we show that expression of ot2/31 by CHO fibroblasts results in the acquisition of collagen and o~3/3~binding. Binding to both of these ligands is inhibited by P1H5, an anti-a2/3~ specific mAb. Results of these in vitro experiments suggest that integrins o~2/3~ and a3/3~ can interact and may do so to mediate ICA in vivo. Thus, c~3/31 mediates keratinocyte adhesion to epiligrin and plays a second role in ICA via {~2~1 9

Integrin α6β4-erbB2 Complex Inhibits Haptotaxis by Up-regulating E-cadherin Cell-Cell Junctions in Keratinocytes

“…Previous studies suggested that ␤1 integrins can mediate cell-cell adhesion via homophilic or heterophilic integrin-integrin interactions involving ␣2␤1, ␣3␤1, and ␣4␤1 (27)(28)(29)35), whereas our data indicate the involvement of AJs. The role of ␤1 integrins in cell-cell adhesion was questioned, because a blocking anti-␤1 mAb did not interfere with intercellular junction organization (36).…”

“…Thus, in this experimental setup, clustering of both Ln-5-binding integrins ␣3␤1 and ␣6␤4 can increase E-cadherin homophilic interactions in the three cell types tested. An involvement of integrin ␣3␤1 in mediating cell-cell adhesion has been demonstrated before (27)(28)(29). However, these are the first results indicating that AJs play a role in this process.…”

Induction and Repression of Collagenase-1 by Keratinocytes Is Controlled by Distinct Components of Different Extracellular Matrix Compartments

“…The type I collagen-binding receptor, ␣2␤1, is constitutively expressed on keratinocytes (22,23), and as we reported recently, this integrin transduces collagen-mediated induction of collagenase-1 (5). Similarly, collagen stimulates collagenase-1 expression in fibroblasts via ligand binding to ␣2␤1 (24,25).…”

Integrins and human intestinal cell functions

“…The alpha2 and alpha3 subunits were found at the basal domain of intestinal cells according to strict complementary staining patterns along the crypt-villus axis, the alpha2 subunit being predominant in the crypts and alpha3 on the villus (62,82,86). It is noteworthy that both of these subunits were also localized at the lateral domain of enterocytes, where they can serve as mediators of intercellular adhesion (92), and that the population of cells exhibiting this lateral staining extends beyond the crypt and villus compartments for the alpha2 and alpha3 subunits, respectively (6). On the other hand, the alpha6 subunit was uniformly distributed at the base of epithelial cells from the bottom of the crypt to the tip of the villus (62, [80][81][82]93).…”